Radiometric dating, or radioactive dating as it is sometimes called, is a method used to date rocks and other objects based on the known decay rate of radioactive isotopes.
The methods work because radioactive elements are unstable, and they are always trying to move to a more stable state. This process by which an unstable atomic nucleus loses energy by releasing radiation is called radioactive decay.
The thing that makes this decay process so valuable for determining the age of an object is that each radioactive isotope decays at its own fixed rate, which is expressed in terms of its half-life.
In contrast, Earth’s most abundant lava rocks, which represent the mantle and make up the major oceanic ridges, have values between 0.703 and 0.705.
This difference may appear small, but, considering that modern instruments can make the determination to a few parts in 70,000, it is quite significant.
Free 5-day trial Radiometric dating is used to estimate the age of rocks and other objects based on the fixed decay rate of radioactive isotopes.
Learn about half-life and how it is used in different dating methods, such as uranium-lead dating and radiocarbon dating, in this video lesson. As we age, our hair turns gray, our skin wrinkles and our gait slows.These whole-rock ages were approximately correct, but a much more precise mathod is now in use.The strategy now used is to plot an isochron, but to correct for the existence of primordial Sr 87, we plot the ratios (Sr-87)/(Sr-86) versus (Rb-87/Sr-86).Unfortunately, there is a lot of primordial Strontium 87 around, making it very hard to tell how much was present when the rock formed and how much formed later as a result of radioactive decay.Fortunately, there is another isotope of strontium around, Strontium 86. Furthermore, since the two isotopes differ by only about 1% in weight, they do not undergo appreciable fractionation from physical processes.Rubidium 87 decays to Strontium 87 with a half life of xx my.